1. Field of the Invention
The present invention relates to off center one spot nutator fulcrum rocking bearings and bearing assemblies.
2. Description of the Prior Art
The prior art includes a variety of nutator assemblies, including, for example, a U.S. Pat. No. 4,699,576 by Durand and ten references cited in it. Few if any are of any commercial importance because of low wear life, among other reasons. During nutation, the fulcrum in effect saws on the barrier or strap coupling the two pistons of the nutator, since there is back and forth motion and the pressure is focused on a relatively small area.
One potential cure for the problem would be some type of roller bearing fulcrum to reduce pressure by spreading the contact between fulcrum and barrier over a greater area. Unfortunately, in practice, wear is uneven since the roller bearing is free to rotate or not rotate depending on mechanical conditions. The outer bearing surface soon begins to favor one point with ultimate consequent failure. The solution is a bearing which spreads the load over a greater area thereby reducing pressure and wear and with positive means for controlling motion.
The only prior art known to applicant which addresses this serious problem is Nash, Ser. No. 353,806 (1886) which more than 100 years ago utilized an adjustable fulcrum bearing surface. Nash failed since the adjustment merely multiplied a too short life by a small number. In the past 100 years, a number of patents have issued for a number of good looking nutating pumps, flow meters, or other devices. They all look good because of the inherent advantages of a nutator, but unfortunately, in spite of improvements in materials, none has had a sufficiently long life to be marketable.
Applicant first tried a sleeve bearing equivalent, which was an improvement. Unfortunately, over a period of time, the bearing does develop a preferred point of contact. On occasion turbulance or other forces cause the bearing to go off that preferred point of contact, causing temporary erratic behaviour. Nevertheless, use of a sleeve bearing as used by applicant substantially corrects this 100 year old problem which has prevented marketability of a class of nutating devices because of excess wear due to point contact of moving element and bearing, thereby changing calibration of this type of nutating flow meters or reducing efficiency of this type of nutating pump.